Carbon arc lamp comprising a carbon holder



Mardi 2, 1965 F. oDsTR'n. ETAI.

CARBON Aac LAMP coMPRIsING A CARBON HoLDER Filed Jan. 4, 1965 2 Sheets-Sheet 1 flaw/fe@ @n ff March 2, 1965 F. oDsTRll. ETAL.

cARBoN ARC LAMP cQMPRIsING A CARBON HOLDER Filed Jan. 4, 1963 2 Sheets-me?l 2 United States Patent O narodni podnik, Prerov, Czechoslovakia Filed Jan. 4, 1963, Ser. No. 249,402 Claims priority, application Czechoslovakia, Jan. 19, 1962, PV 377/62 8 Claims. (Cl. S14- 42) The present invention relates to carbon arc lamps, and particularly to a carbon holder adapted to rotate and axially advance a carbon electrode while in contact with a source of electric current.

It is known to equip a carbon arc lamp with a holder having a plurality of rollers which engage the positive carbon electrode and rotate and axially advance the same. The rollers of the known device are symmetrically arranged about the electrode, and their axes of rotation extend in planes which are tangential relative to cylinders about the electrode axis, and are inclined at acute angles to that axis.

An object of the invention is the provision of a carbon holder avoiding certain shortcomings of the known device Which is relatively complex, so bulky as to block a portion of the light beam generated by the arc lamp, and somewhat inconvenient in its operation. More specifically, the invention aims at a carbon holder which can readily be adapted to carbon electrodes of different diameters.

With these and other objects in view, the invention in one of its aspects provides the carbon holder of an arc lamp with three ring members formed with respective openings therethrough and aligned in such a manner that they can simultaneously receive a carbon rod electrode in their openings, the rod being elongated in the direction of ring alignment, and one of the ring members being interposed between the other two. Drive means simultaneously rotate the ring members in respective planes obliquely inclined relative to the direction of alignment. Yieldably resilient means urge the afore-rnentioned one ring member to move into engagement with the received rod in a direction transverse of the direction of alignment, and urge the other two ring members to move into engagement with the rod in a direction substantially o pposite to that transverse direction.

Other features and objects of the invention will hereinafter become more fully apparent from the following description of the annexed drawings, which illustrate a preferred embodiment of the invention, and wherein:

FIG. l shows a carbon holder of the invention in sideelevational section;

FIG. 2 shows the apparatus of FIG. l in front elevational section on the line A-Ag FIG. 3 illustrates the device of FIG. 2 in a different operational position; and

FIG. 4 is a diagram illustrating relative movement of a carbon and a drive ring in the apparatus of FIG. l.

Referring now to the drawing in detail, FIG. l shows an upright supporting frame 1 mounted on a base plate 2. A shaft 3 journaled in the frame 1 is connected to a drive shaft 4 by means of bevel gears 5, 6 and pivotally supports three two-armed levers 7, S, 9 as is best seen in FIGS. 2 and 3. Three gear wheels 10, 11, 12 are ixedly keyed to the shaft 3 and are retained in respective recesses of the levers 7, 8, 9 by covers 30, 31, 32. The recesses also hold respective circumferentially toothed drive rings 13, 14, in meshing engagement with the gear wheels 10, 11, 12 for rotation in planes 35 which are offset from planes K by angles a, the planes K being perpendicular to the axis of the shaft 3.

3,172,003 Patented Mar. 2, 1965 "ice A cylindrical carbon rod 16 passes through aligned openings in respective rst arms of the three levers 7, S, 9 and the central openings of the associated rings 13, 14, 15 in a direction parallel to the axis of the shaft 3. Springs 20, 21 connect the second arms of the lever 8 to the second arms of the levers 7, 9 respectively in such a manner that the internal grooved surfaces of the rings 13, 15 in the recesses of the levers 7, 9 make contact with the carbon rod 16 along a straight line 18, and ring 14 in the recess of the lever 8 makes contact with the carbon rod along a line 19, as shown in FIG. 2, the grooves in the ring surfaces not being explicitly illustrated.

A horizontally elongated ilat bar 23 is rotatably mounted in the frame 1 by two cylindrical trunnions and extends between the second arms of the levers 7, 8, 9. One of the trunnions carries an arm 24 by means of which the bar 23 may be pivoted between the positions respectively illustrated in FIGS. 2 and 3. When in the position of FIG. 2, the width 0f the bar 23 is vertical, and the bar is spaced horizontally from the second arms of the levers 7, S, 9 in the direction of its thickness by clearances 22. In the position of the FIG. 3, the bar width is horizontal, and the bar abuttingly engages the levers and holds them apart against the restraint of the springs 20, 21 so that the carbon rod 16 is centered in the rings 13, 14, 15.

The other trunnion of the bar 23 carries a disk cam 23. The mechanism which supplies electrical current to the carbon rod 16 includes a fixed contact jaw 25 mounted on the frame 1, and a movable contact jaw 26 mounted on one end of a pin 29. A helical compression spring 27 interposed between a surface of the frame 1 and a collar 33 on the pin 29 urges the jaw 26 toward the jaw 25 for clamping the carbon rod 16 between the jaws, and also biases the free end of the pin 29 towardL the cam 2S. The position of the cam 23 illustrated in FIG. 1 corresponds to that of the bar 23 shown in FIG. 2, and the cam is spaced a distance 34 from the free end of the pin 29.

The afore-described apparatus operates as follows:

A drive mechanism of which only the shaft 4 is shown,

causes rotation of the shaft 3 of the gear wheels 10, 11, 12 and of the rings 13, 14, 15. y The frictional engagement of the rings with the carbon rod 16 causes simultaneous rotation and axial advance of the rod, the point of contact between one ring and the rod moving along the rod in a helix 17 as shown in FIG. 4. The force S transmitted from the ring to the rod under the contact pressure of the associated spring 29 and 21 has a component P in the direction of the rod axis O and a rotational component R which are related to the force S by a vector rectangle having sides P and R and the diagonal S, the diagonal S and side R enclosing the aforementioned angle a.

When the bar 23 is pivoted from the position of FIG. 2 to the position of FIG. 3 by the arm 24 through an angle of the rings 13, 14, 15 are aligned so as to release the carbon rod 16, and the movable contact jaw 26 is simultaneously lifted from the rod by the cam 28. The rod may be withdrawn and replaced by a new carbon rod.

If the diameter of the newly inserted rod is different from that of the original rod, the Contact jaws 25, 26 are replaced by others dimensioned for conforming engagement with the rod of different diameter, but no other changes are necessary. When the arm 24 is returned to its initial position, the rings 13, 14, 15 engage the surface of the new rod under the force of the springs 20, 21, and the contact jaws 25, 26 are closed on the rod. Any irregularity or difference in the diameters of the original and the newly inserted rod is compensated for by the springs 20, 21, 27.

It is essential for proper operation of the carbon holder that clearances 22, 34 be maintained while the bar 23 is in the operative position shown in FIGS. 1 and 2 so that the springs may perform their compensating function.

The carbon holder of the invention has small dimensions so that it does not interfere with the light output of an electric arc extending from the held carbon rod. Surface defects of the carbon rod do not affect operation of the holder because of the resilient mounting ofthe rings which transmit motion from the drive shaft 4 to the carbon rod 16. For the same reason, warping of the rod and variations in diameter are well tolerated, but changes in diameter may require replacement of the contact jaws 25, 26.

The carbon holders of the invention are therefore used to advantage in carbon arc lamps of optical projectors and in other applications in which a small carbon holder capable of simultaneously rotating and axially advancing a carbon rod is needed.

What we claim is:

1. A carbon holder for a carbon arc lamp comprising, in combination:

(a) a support;

(b) a shaft rotatably mounted on said support;

(c) a plurality of lever members pivotally supported on said shaft in axially spaced relationship;

(d) a ring member on each lever member, each ring member being formed with an opening therethrough;

(e) yieldably resilient means urging said lever members to pivot on said shaft into a position of engagement in which said ring members are aligned for simultaneously receiving a carbon rod member in the openings thereof and for abuttingly engaging the received carbon rod member, said carbon rod member having an axis;

(f) drive means for rotating said shaft on said support;

(g) motion transmitting means operatively interposed between said shaft and said ring members for rotating the same in respective planes obliquely inclined relative to said axis when said shaft is rotated; and

(l1) contact means for supplying electric current to said rod during rotation of said ring members.

2. A carbon holder as set forth in claim 1, further comprising a Hat bar member mounted on said support for movement between one position in which said bar member is spaced from said lever members, and another position in which said bar member holds said lever members away from said position of engagement against the urging of said yieldably resilient means; a cam member mounted on said bar member for movement therewith; and cam follower means, said contact means including a contact member movable toward and away from a position of contact with a carbon rod member received in said openings of the ring members, and said cam follower means being engageable with said cam member and being operatively connected to said movable contact member for moving the same away from said position of Contact when said bar member moves from said one to.said other position thereof.

3. In a carbon holder for an arc lamp, in combination:

(a) three ring members formed with respective openings therethrough and aligned in a predetermined direction for simultaneously movably receiving a carbon rod member in said openings thereof, said rod member being elongated in said direction,

(l) one of said ring members being interposed in said direction between the other two ring members;

d (b) drive means for simultaneously rotating said ring members in respective planes obliquely inclined relative to said direction; and

(c) yieldably resilient means urging said one ring member to move into engagement with the received rod member in a direction transverse of said predetermined direction, and for urging said other two ring members to move into engagement with said rod member in a direction substantially opposite to said transverse direction.

4. In a carbon holder as set forth in claim 3, said planes being substantially parallel.

5. In a carbon holder as set forth in claim 3, said transverse direction being perpendicular to said predetermined direction.

6. In a carbon arc lamp, in combination:

(a) a support;

(b) a rod-shaped electrode; and

(c) electrode holder means for rotating said electrode about an axis and for axially advancing said electrode, said holder means including (1) a plurality of lever means mounted for pivoting movement on said support about a pivot axis substantially parallel to the axis of rotation of said electrode,

(2) three ring members extending about said electrode and axially spaced from each other, whereby one of said ring members is axially interposed between the two other ring members, said ring members being mounted on said lever means for pivoting movement therewith about said pivot axis,

(3) actuating means for actuating rotation of said ring members in respective planes obliquely inclined relative to said axis of rotation, and (4) yieldably resilient means urging said one ring member to move about said pivot axis in one direction and for urging the other two ring members to move about said pivot axis in the other direction until said ring members abut against said electrode. 7. In a lamp as set forth in claim 6, said actuating means including a shaft journaled in said support, said lever means being pivotally mounted on said shaft, drive means for actuating rotation of said shaft about said pivot axis, and motion transmitting means interposed between said shaft and said ring members for rotating the same.

8. In a lamp as set forth in claim 7, said lever means including three lever members pivotally mounted on said shaft, said ring members being mounted on said lever members respectively, said yieldably resilient means including spring means engaging said lever members, and control means for selectively holding said lever members in an inoperative position against the force of said spring means, said ring members in said inoperative position of said lever members being spaced from said electrode.

References Cited by the Examiner UNITED STATES PATENTS Re. 21,346 2/40 Brandt 314-41 X 2,136,082 11/38 Krieg et al. 314-41 2,234,274 3/41 Prinz 314-41 RICHARD M. WOOD, Primary Examiner.

JOSEPH V. TRUI-IE, Examiner. 

1. A CARBON HOLDER FOR A CARBON ARC LAMP COMPRISING, IN COMBINATION: (A) A SUPPORT; (B) A SHAFT ROTATABLY MOUNTED ON SAID SUPPORT; (C) A PLURALITY OF LEVER MEMBERS PIVOTALLY SUPPORTED ON SAID SHAFT IN AXIALLY SPACED RELATIONSHIP; (D) A RING MEMBER ON EACH LEVER MEMBER, EACH RING MEMBER BEING FORMED WITH AN OPENING THERETHROUGH; 